Effect of initial microstructure on the hot deformation behavior of a Ni3Al-based alloy

Abstract

To investigate the effect of initial microstructure on the hot deformation behavior of a Ni3Al-based alloy, the isothermal compression tests were conducted on the studied alloy with two different microstructures at 1100 °C and 1200 °C with strain rate range of 0.01–1 s−1. The results show that the hot deformation behavior of the Ni3Al-based alloy is sensitive to the initial microstructure, particularly under low deformation temperature and high strain rate. The flow curves signified that the peak stress and the magnitude of the stress drop for the alloy with coarse γ′ precipitates are higher than those for the alloy with fine γ′ precipitates at a given temperature and strain rate. Besides, it is found that the critical conditions are affected by deformation temperature, strain rate and initial microstructure. Both the critical stress and strain of dynamic recrystallization significantly decreases with the increase of strain rate and decrease of deformation temperature. For different initial microstructures, the critical stress and strain for the alloy with coarse γ′ precipitates are higher than that for the alloy with fine γ′ precipitates. The critical ratios of the studied alloy were also determined. The dissolution of coarse γ′ precipitates easily occurs and the dissolution rate can be accelerated at the sufficiently high temperature, which leads to that the effect of initial microstructure on hot deformation behavior of the Ni3Al-based alloy is weakened.